low oil pressure on idle

[overs10ded]

Blowing the fuse is pretty strange for an oil pressure sender. Possibly the wrong sender? There are two different types of electrical senders and I think the "idiot light" sender only has a low pressure switch that activates the "idiot light" and the other is used for an analog type oil pressure gauge and uses voltage based on pressure to move the needle on the electrical gauge. Could be the power wire for the light coming from the fuse-block is shorting somewhere also??

I found a VDO mechanical off ebay that I got for $10 w/copper line w/fittings plus a plastic line that I'm using with an A/C vintage 60's NOS vacuum gauge I also got for $10 on ebay. If using a mechanical gauge permanently, ONLY use the brass or copper line even though most all gauges come with plastic line-IT WILL BREAK or burn and you will loose oil!!! For a test the plastic is OK but don't trust it!

I also want a tach! I would like to find an SR5 instrument cluster and R&R mine with the SR5 like dlb suggested to me, but don't know if I have that much patience...nope, patience is used up. I figure I'll get a small tach and then if ever I find an SR5 instrument cluster...

Good times!
Bruce

[marlinh]

One thing to note, driving a vehicle with too much oil in the crankcase can cause aeration of the oil in the sump when the crankshaft counterweight passes through. This causes air bubbles to be created in the sump which then gets picked up by the oil pump and travels through the galleries. Long term operation like this can cause bearing failure. I saw this happen in a brand new engine that the owner overfilled. (Long story as to why) There is a reason for the Full line on a dipstick.

[celtglen]

One thing to note, driving a vehicle with too much oil in the crankcase can cause aeration of the oil in the sump when the crankshaft counterweight passes through. This causes air bubbles to be created in the sump which then gets picked up by the oil pump and travels through the galleries. Long term operation like this can cause bearing failure. I saw this happen in a brand new engine that the owner overfilled. (Long story as to why) There is a reason for the Full line on a dipstick.

Wisdom rules!

[simon84]

I am now having the same issue as DLB with my 87 tercel (4A motor with weber).
I just did an oil change to see if that helped and once it warmed up the oil light was blinking on at idle.
I have ordered a new OPS and will get that tomorrow. I am looking at ordering a gauge online.
Any way to tell if it is gas leaking in from the fuel pump? I smelled the oil and it smelled kinda gassy but not sure if it's just kinda how oil smells.
Otherwise it is running fine. Not overheating.
Also looking at an oil temp gauge but not sure where that sensor would go on the engine. Has anyone put an oil temp gauge on theirs?

[dlb]

simon, remember that if you get a gauge, you will need the adapter to connect it to the block. i can't remember the measurements offhand but they're in one of my posts on the first page of this thread.

[Petros]

oil temp gauges are used in off road vehicles and race cars, they just monitor the temp of the oil in the oil pan, if you install one the best way is to find an oil pan, drill a hold in the side (below the oil lever) in a convenient location, and have a pipe fitting (female) welded to the pan at the hole. the sender pokes the end into the oil in the sump.

I put one on one of my first street performance builds (35 years ago?), a 122S volvo that I also wanted to rally cross. I found that the oil temp always stayed low, no matter the outside temp, even on long up hill grades. the only time it when up was when I has sustained high rpm operation (like on the few times I actually did enter a rally cross with it). So on a car where you drive it near red-line all the time, it is a good thing to have. Otherwise it is just there to amuse you and impress your friends. Most people do not even know why you would need one and what "proper" oil temp is supposed to be (about 200 deg is optimum, which you almost never reach in a daily driver). I have never felt the need for one since on any car I have owned.

OIl pressure is far more important, it will let you know if you are low on oil (unsteady pressure), or if your bearings or oil pump are worn (low pressure particularly at idle). But having an idiot light is very important so to know if your oil pressure should go below about 7 psi since it is more likely to get noticed. It would be nice to rig the car so you get both an oil pressure gauge and still have the idiot light.

[simon84]

Thanks for all the tips thus far...

I am still having oil pressure issues...

Yesterday I got the new OPS and took a look at things. I quickly determined that it was going to be more involved than just pop out the old one and in with the new. Alternator is going to have to come out. In doing this I pulled the connector off the OPS and then replaced it. After this, the oil pressure light was working as I would expect. This is to say, it comes on when i turn on the ignition and promptly goes off when the engine starts. Goes on if I stall out the engine but only once the engine is stopped. No flickering on low idle.
Today I start it up and no oil light comes on at all when ignition is on. I figure that the OPS might be the problem so I pull the alternator and put in the new OPS. Now the oil light is on all the time.

Could this OPS be the wrong part? I have had a bit of bad luck sourcing parts lately. I did ask for the OPS for a 4A engine (ie 88 corolla, SOHC, 1.6 litre 4A motor)
Could my oil pump be toast? I realize the answer could be yes.
Drove around a bit today and it's running fine, not overheating.
I have an oil pressure gauge on order. Probably take a couple of weeks at least.

Thanks in advance for any more tips.

[dlb]

i'm not positive but am confident the 3a and 4a engines use the same OPS. you can go on rockauto or whatever and compare part #s between the two to confirm this.

the inconsistent oil light is weird. it sounds to me like there might be a wiring issue, a spot where the wire sheath is worn through and allowing the wire to ground out on something. but i do think it's a good idea to put a gauge on it and confirm your OP is ok at idle. i think i got mine at canadian tire for $15 or $20.

[simon84]

The wire short is a good theory since when I was in there the wire would have been moved around a bunch. So it is likely that it went from no light this morning (not shorting out at all) to oil light on all the time (shorting out constantly).
Cambodian tire had nothing today when I went there... I will check online for that.
I will check those part #s online as well.

Thanks for putting some brainpower on this DLB. Hope you are enjoying your trip!

[Petros]

one of the reasons I have an oil pressure gauge is my oil like would flicker on and off at random times, or show flickering on/off. with the gauge I can see there is a problem with the idiot light system, and saw that the flicker would still happen even though there was no sender installed at all. I have not bothered to hunt down the short, but that likely what is happening.

funny thing is when it flickers on occasionally I still get a moment of fear and panic when I see that light, even though I know it is not even connected. I got to find that darn short in the wiring!